DLD: a multi-functional mitochondrial enzyme. An enzymatic component of the mitochondrial glycine cleavage system, the pyruvate dehydrogenase complex (PDHC), the alpha-ketoglutarate dehydrogenase complex, and the branched-chain alpha-keto acide dehydrogenase complex. Is the E3 component of the PDHC that catalyzes the overall conversion of pyruvate to acetyl-CoA and CO2. The E3 component has dihydrolipoamide dehydrogenase activity. The PDHC contains 20-30 copies of pyruvate decarboxylase tetramers (2 alpha:2 beta)(E1), 60 copies of dihydrolipoamide acetyltransferase (E2), six homodimers of dihydrolipoamide dehydrogenase (E3), plus E3 binding proteins. Defects in DLD are a cause of maple syrup urine disease (MSUD), characterized by mental and physical retardation, feeding problems and a maple syrup odor to the urine. The keto acids of the branched-chain amino acids are present in the urine, resulting from a block in oxidative decarboxylation. Differentially expressed in the Wernicke's Area from patients with schizophrenia. Inhibited by 5-methoxyindole-2-carboxylic acid (MICA).
Protein type: Amino Acid Metabolism - valine, leucine and isoleucine degradation; Amino Acid Metabolism - glycine, serine and threonine; Mitochondrial; EC 1.8.1.4; Carbohydrate Metabolism - citrate (TCA) cycle; Carbohydrate Metabolism - pyruvate; Carbohydrate Metabolism - glycolysis and gluconeogenesis; Oxidoreductase
Cellular Component: nucleoplasm; mitochondrion; mitochondrial matrix; pyruvate dehydrogenase complex; oxoglutarate dehydrogenase complex; acrosomal matrix; myelin sheath; cilium
Molecular Function: mercury (II) reductase activity; FAD binding; mercury ion binding; lipoamide binding; dihydrolipoyl dehydrogenase activity; NADP binding; NAD binding
Biological Process: lipoate metabolic process; acetyl-CoA biosynthetic process from pyruvate; regulation of membrane potential; mitochondrial electron transport, NADH to ubiquinone; cell redox homeostasis; detoxification of mercury ion; gastrulation; proteolysis; dihydrolipoamide metabolic process; sperm capacitation; aging; 2-oxoglutarate metabolic process
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